Turbomachines, such as gas turbine engines, typically include a fan section, a compression section, a combustion section, and a turbine section. Turbomachines may employ a geared architecture connecting portions of the compression section to the fan section. Turbomachines include various seals. The seals may be lift-off seals.
Some lift-off seals rely exclusively on hydrodynamic forces to move the seal to a position appropriate for establishing a sealing film of air. At low pressures, low speeds, high biasing loads, etc., the hydrodynamic forces may be inadequate. The lift-off seal may undesirably touchdown if the hydrodynamic forces are inadequate.
Other lift-off seals rely exclusively on hydrostatic forces to move the seal to a position appropriate for establishing the sealing film of air. Under some operating conditions, the hydrostatic forces are inadequate and touchdown may undesirably occur.